SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b9a9ac31cfd142f8ecfa43825e6f4e7d4277d5f0d83fcb64c45c4c639806b50' 
  AND token = 'lWQ3r0JU7Tscvv2zrDWWVeewkBQ73KhaA/q8Zm2oGGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00073

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}